bind-gen: Support accumulation of include headers on demands in CodeNode

Bug: 839389
Change-Id: Ibb15a1d8d27474d0b46af42525958758cc4ac85c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1906850
Commit-Queue: Yuki Shiino <yukishiino@chromium.org>
Reviewed-by: Hitoshi Yoshida <peria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#714151}

third_party/blink/renderer/bindings/scripts/bind_gen/code_node.py

@@ -144,6 +144,7 @@ class CodeNode(object):
         self._template_vars = {}
 
         self._accumulator = None  # CodeGenAccumulator
+        self._accumulate_requests = []
 
         self._renderer = None  # MakoRenderer
 
@@ -179,6 +180,11 @@ class CodeNode(object):
         finally:
             self._is_rendering = False
 
+        if self._accumulate_requests:
+            assert self.accumulator
+            for request in self._accumulate_requests:
+                request(self.accumulator)
+
         return text
 
     def _render(self, renderer, last_render_state):
@@ -286,6 +292,14 @@ class CodeNode(object):
         assert self._accumulator is None
         self._accumulator = accumulator
 
+    def accumulate(self, request):
+        """
+        While rendering the code node, |request| will be called with the
+        argument of self.accumulator.
+        """
+        assert callable(request)
+        self._accumulate_requests.append(request)
+
     @property
     def renderer(self):
         # Always use the renderer of the root node in order not to mix renderers

third_party/blink/renderer/bindings/scripts/bind_gen/codegen_accumulator.py

@@ -25,6 +25,10 @@ class CodeGenAccumulator(object):
     def add_include_headers(self, headers):
         self._include_headers.update(headers)
 
+    @staticmethod
+    def require_include_headers(headers):
+        return lambda accumulator: accumulator.add_include_headers(headers)
+
     @property
     def class_decls(self):
         return self._class_decls
@@ -34,3 +38,7 @@ class CodeGenAccumulator(object):
 
     def add_class_decls(self, class_names):
         self._class_decls.update(class_names)
+
+    @staticmethod
+    def require_class_decls(class_names):
+        return lambda accumulator: accumulator.add_class_decls(class_names)